Detecting multiatomic composite states in optical lattices

We propose and discuss methods for detecting quasimolecular complexes which are expected to form in strongly interacting optical lattice systems. Particular emphasis is placed on the detection of composite fermions forming in Bose-Fermi mixtures. We argue that, as an indirect indication of the composite fermions and a generic consequence of strong interactions, periodic correlations must appear in the atom shot noise of bosonic absorption images, similar to the bosonic Mott insulator [ S. Fölling et al. Nature (London) 434 481 (2005)]. The composites can also be detected directly and their quasimomentum distribution measured. This method—an extension of the technique of noise correlation interferometry [ E. Altman et al. Phys. Rev. A 79 013603 (2004)]—relies on measuring higher order correlations between the bosonic and fermionic shot noise in the absorption images. However, it fails above a certain number of the constituents due to a dramatic increase of uncorrelated noise.